Previously, magnetic recording media such as video tapes, audio tapes and magnetic disks have been widely used which comprise non-magnetic supports having thereon magnetic layers, said magnetic layers containing ferromagnetic iron oxide, Co-modified ferromagnetic iron oxide, CrO.sub.2, ferromagnetic alloy particles, ferromagnetic hexagonal ferrite or the like. In particular, ferromagnetic hexagonal ferrite is considered to be excellent in high-density recording characteristics because of its small particle size, its tabular shape and its axis of easy magnetization perpendicular to the plate surface. However, the difficulty of dispersion due to its high coagulation results in inferior surface properties, and also in orientation inferior to that of other magnetic particles. Ferromagnetic hexagonal ferrite have not therefore been able to provide sufficient electromagnetic characteristics, although it has the potential for a ferromagnetic particle for high-density recording media. Hexagonal ferrite further has the problem that long-wavelength characteristics is inferior because of its low saturation magnetization (.sigma.s).
In order to solve these problems, JP-A-62-204427 (the term "JP-A" as used herein means an "unexamined published Japanese patent application") and JP-A-60-223018 disclose magnetic recording media each comprising a magnetic layer containing a ferromagnetic hexagonal ferrite particle and another magnetic layer combined therewith, whereby high output can be obtained over a wide range of recording wavelength. JP-A-4-119520, JP-A-63-71926 and JP-A-61-220125 disclose magnetic recording media each having a multiple-layer structure with another non-magnetic layer. However, these attempts are not satisfactory as high-density recording media now required.
JP-A-63-281221 and JP-A-4-19815 disclose the control of surface roughness (Ra). This decreases noise effectively, but is insufficient particularly for improving characteristics in a short-wavelength recording region. JP-A-61-24010 and U.S. Pat. No. 4,666,770 disclose glossiness. However, this is insufficient as high-density recording media now required.
As one concept considered from a ferromagnetic particle, means for improving the recording density include minimization of a magnetization unit on a magnetic layer and arrangement thereof in a running direction of a magnetic head, enlargement of magnetization, and arrangement of magnetic orientation corresponding to the running direction of the magnetic head. For the magnetization unit, it is effective to reduce the size of particles, or to arrange the magnetic particles densely on a surface of the magnetic layer. With respect to the magnetization, the magnetic characteristics of the magnetic particles themselves and the filling degree thereof in the magnetic layer are important. For the magnetic orientation, arrangement of the ferromagnetic particles with the axis of easy magnetization arranged is considered to be important. In any event, the recording density is significantly influenced by the shape of the magnetic particles and the arrangement thereof in the magnetic layer.
As described above, the prior art for obtaining high-density recording magnetic media includes a reduction in particle size of the ferromagnetic particles, an increase in saturation magnetization (.sigma.s) of the ferromagnetic particles, and an increase in orientation of the ferromagnetic particles in the magnetic layer. These various proposals are insufficient yet for realizing high-density recording, for example, in a recording wavelength of 0.5 .mu.m or less.